Pour beer and seltzer water or soda into the bowl of a blender or food processor (or a stick blender can be used). Sprinkle in pepper, mustard, salt and onion powder and oil. Pulse until combined. Add flour last, and process only until mixed. Batter may still be slightly lumpy, but almost smooth. If too pasty, add a teaspoon of water at a time until mixture has the consistency of a pancake batter.
Whisk egg white until frothy in a shallow bowl. Gently stir in contents of food processor, mixing until combined.
Slice large sweet onions into rings. Separate rings. Soak in a small amount of milk for 10 minutes. Drain and lightly sprinkle with onion powder, then dip in batter.
Fry small batches in hot oil (365F), turning once, gently to brown evenly. Remove using a slotted spoon and drain on paper towels before serving. Season with salt and pepper (a little hot salt or cayenne, if desired) while still hot from fryer.
Serve in paper baskets lined with paper towels. Great with batter-fried fish.
Submitted by: CM
